Cloning and characterization of aspartic protease 3 of Toxoplasma gondii

Abstract

Aspartic proteases are proposed as attractive drug targets of pathogens including apicomplexan parasites. In the present study, a gene encoding aspartic protease 3 of Toxoplasma gondii (TgASP3) was cloned, expressed and characterized. The gene fragment of putative functional domain of TgASP3 was expressed in Escherichia coli as a recombinant glutathione-S-transferase (GST) fusion protein (rTgASP3d). The native TgASP3 with molecular mass of 66-kDa from T. gondii tachyzoites was identified by Western blot analysis using anti-rTgASP3d mouse serum. In addition, the result from immunofluorescent antibody test (IFAT) using anti-rTgASP3d suggests that the native TgSAP3 is localized in the cytoplasm of T. gondii tachyzoites. On the other hand, the growth of T. gondii tachyzoites was significantly inhibited by an aspartic protease inhibitor-pepstatin A. These results suggest that the TgASP3 might be a novel therapeutic target for T. gondii infection.